Split bushing



NW. 3, 19% R. L. BLEICHER 9 SPLIT BUSHING Filed Dec. 21, 1961 IN V EN TOR.

Ferforators, Inc, Dayton, Qhio, a corporation of Ohio Fiied Dec. 21, 1961, Ser. No. 161,191 Claims. (Cl. 308-237) This invention relates to a novel guide bushing.

A bushing is a highly essential device having a wide variety of application. When serving as a guide for a reciprocating tool it is generally formed in one piece and expanded at its entrance end to facilitate the entrance and passage of the tool therethrough. This expansion is conventionally effected by a countersinking operation or by employing a conical grinding element in a boring operation. The countersinking operation produces shoulders or ridges in the entrance wall. The shoulders or ridges tend to cause wear or abrupt deflection of the reciprocating tool with obvious undesirable consequences. On the other hand, a conical grinding element is quite expensive in the first instance. Moreover, it wears rapidly and must be dressed quite frequently. For this reason it is difficult to get uniform or precision results when employing the conical grinding element.

The present invention is significant in that it provides an improved guide bushing which may be more simply fabricated and in a manner to avoid the occurrence of the problems above described. Moreover, it provides guide bushings the entrance ends of which, in a preferred form, are provided with parabolically contoured surface portions affording a safe entrance and precision alignment for tools passing therethrough.

A primary object of the invention is to provide improvements in guide bushings and the like rendering them economical to fabricate, more efficient and satisfactory in use and adaptable to a wide variety of applications.

A further object of the invention is to provide a guide bushing with an improved entrance surface the major extent of which has a generally parabolic contour.

Another object of the invention is to provide a split guide bushing having improved functional characteristics.

A further object of the invention is to provide a guide bushing possessing the advantageous structural features, the inherent meritorious characteristics and the mode of operation herein mentioned.

With the above and other incidental objects in view as will more fully appear in the specification, the invention intended to be protected by Letters Patent consists of the features of construction, the parts and combinations thereof, and the mode of operation as hereinafter described or illustrated in the accompanying drawings, or their equivalents.

Referring to the accompanying drawing wherein is shown one but obviously not necessarily the only form of embodiment of the invention,

FIG. 1 is a view of the entrance end of a bushing in accordance with the invention;

FIG. 2 is an elevational view of the device of FIG. 1;

FIG. 3 is a side elevation view illustrating a method of fabricating the improved bushing in accordance with the invention;

FIG. 4 is an end view of the structure shown in FIG. 3; and

FIG. 5 is a view in cross-section taken substantially along the line 5-5 of FIG. 1.

Like parts are indicated by similar characters of reference throughout the several views.

As seen in the drawings, a split guide bushing 1 is provided in assembled form to have an outer periphery which is generally circular in cross-section. The bushing 1 consists of two'identical generally hemi-cyclindrical .United States Patent 0 segments 2 having abutting planar surfaces 3. Centrally and longitudinally of each surface 3 is a depression 4 which is uniformly rectangular save at its entrance end 5. In the mating of the segments 2 the depressions 4 mate to mutually define a through passage 6 in the bushing 1 which is rectangular in cross-section except at its entrance end. The mating surface portions 7 of the segments 2 at the entrance end of the passage 6 are formed to mutually define a smooth surface which in planes parallel to the surfaces 3 is generally parabolic in configuration and in planes perpendicular thereto is V-shaped in configuration. The net effect is to provide an entrance surface having the general contour of a paraboloid, the apex of which merges uniformly into the rectangularly oriented sides of the segments 2 defining the passage 6.

The guide bushing above described is fabricated in the following manner. Two hemi-cylindrical segments 2 are suitably formed such as by splitting a cylindrical rod. Each segment is then subjected to application of a cutting tool operated to form a uniformly rectangular depression 4 centrally and longitudinally of its surface 3. Each segment 2 is then positioned in a holder, as shown in FIGS. 3 and 4 of the drawings, to dispose its surface 3 at a 30 angle to a horizontal. Then a conventional cutting wheel 8 having a cutting surface that is uniformly arcuate in cross-sectional contour is oriented in a plane perpendicular to the surface 3, in line with its central longitudinal axis. The wheel 8 is large in diameter in relation to the length of cut to be made and is advanced on a direct horizontal line. Intercepting the surface 3, it effects a single merely straight line cut therein at a 30 angle relative thereto. The length and depth of the cut is determined by the vertical adjustment of the wheel 8 with reference to the surface 3 of the segment 2 and is limited to one end of the surface 3. In this simple fashion an entrance depression is effected in the surface 3 which is of smooth continuous character the contour of which is parabolic in planes parallel to the surface 3 and that of a straight line inclined to the surface 3 in planes at right angles thereto. The approximately straight line out but this grinding wheel 8, the edge of which is uniformly arcuate in cross-section, thereby produces a depression having the general contour of a section of a paraboloid that merges smoothly into the edges of the rectangular depression 4 without leaving shoulders, ridges or burrs.

Both segments of the blank for the bushing 1 being uniformly cut, their planar surfaces 3 and depressions i will accurately mate on their assembly. A guide bushing thus derives, as previously described, having a rectangular through passage 6 the entrance end of which is generally parabolically expanded in a smooth uniform fashion. When applying the bushing so formed to a stripping plate, for example, on advance of a punch or cutting element to move through the bushing the generally paraboloid contour of the major portion of the entrance surface of the passage 6 will gently guide it to its proper alignment to accomplish its desired cutting function.

While the depressions 4 are illustrated as rectangular and the invention improvements particularly definitive when applied thereto, the shape of the depressions obviously need not be so limited. Nor need the angle at which the wheel or grinding element 8 is applied to surface 3 be limited to 30. However, such angle should preferably not exceed 45 The above method involves the use of simple and conventional equipment, thereby enabling a substantial reduction of bushing cost.

It will be seen from the above that the fabrication of embodiments of the present invention does not require the use of expensive conical grinding elements or unsatisfactory counter-sinking devices such as normally e employed in the fabrication of conventional guide bushingsp -M'oreover, the invention guide bushings, as'fabricated in their split form, provide a through passage having an entrance end which is parabolically expanded in a smooth uniform fashion.' Thus, the invention guide bushing istnot only economical to fabricate but it also provides optimum efiiciency and' minirnum maintenance problems in its use.

' From the above description it will be apparent that there is thus provided a device of the character described "possessing the particular features of advantage before "enumerated as desirable, but-which obviously is susceptible of modification in its form, proportions, detail const'ruction and arrangement of parts without departing from the principle involved or sacrificing any of its advantages.

" While in order to comply with the statute the invention has-been described in languagemore or less specific as to structural features, it is to be understood that the invention is not limited to the specific features shown, but that the means and construction herein disclosed comprise but one of several modes of putting the invention into'effecL-and the invention is therefore claimed in any of its forms or modifications within the legitimate and valid scope of the appended'claims.

' Having thus described my invention, I claim:

1. A guide bushing including mating half sections having surfaces mutually defining a through passage thereto' define a passage therebetween, at least a portion of said surfaces having a parabolic contour.

4. A guide bushing including shell segments formed to define a through passage on assembly, depressions longitudinally of; the surfaces of said segments defining said passage, at least a portion ofwhich having a parabolic contour to one end.

5. A guide bushing including a plurality of mating segments having depressions longitudinally of one surface arranged to define a through passage, said depressions being generally rectangularly contoured in cross-section and parabolically expanded to their entrance end.

References Cited in the file of this patent "UNITED STATES PATENTS 1,588,606 '-Oden June 15, 1926 2,376,724 Rice May 22, 1945 2,611,435 Janiszewski Sept. 23, 1952 2,651,551 Ingram Sept. 8, 1953 

2. A GUIDE BUSHING INCLUDING MEANS DEFINING A SHELL HAVING A PASSAGE THERETHROUGH, SURFACE PORTIONS OF SAID SHELL PROVIDING THE ENTRANCE TO SAID PASSAGE HAVING A GENERALLY PARABOLIC CONTOUR. 